1. Field of the Invention
The present application relates generally to dampers, and more specifically, to an adjustable lead-lag damper.
2. Description of Related Art
In articulated rotors, blade lead-lag, feathering and flapping motions will all potentially contribute to one-per-revolution damper motion, which affects hub and blade loads as well as damping of the lead-lag mode.
Helicopter with articulated rotors require the use of lead-lag damper to remain stable on the ground and in the air. However, in addition to providing damping to the rotor, lead-lag dampers will also generate loads, which are generally a function of the one-per-revolution damper motion (more motion, more load). Furthermore, it is known that one-per-revolution damper motion in conjunction with motion at the lag mode frequency, reduces the lead-lag damping of the rotor system (more motion, less damping). Therefore, minimizing one-per-revolution damper motion would be beneficial in terms of both reducing loads and increasing the dual frequency damping of the lead-lag mode.
This one-per-revolution damper displacement is essentially related to the rotor geometry (location of the blade pivot points and damper attachment points) and the blade lead-lag, feathering and flapping motions. In addition, the phase shift between these blade motions is important, as different phasing could result in either an additive or cancelling effect, increasing or reducing overall damper displacement.
Although the foregoing developments in the field of lead-lag dampers represent great strides, many shortcomings remain.
While the system and method of the present application is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular embodiment disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the process of the present application as defined by the appended claims.